Electrolyte disturbance

Question 1

What are the signs and symptoms of hypokalaemia?

Answer 1

weakness, hypotonicity, ventilatory failure, hyporeflexia, cramps, tetany, palpitations, light-headedness, constipation, charactertistic ECG changes , dysarrhythmias if severe -> rhabdomyolysis may occur - muscle pain, swelling, tenderness and red-brown urine

Question 2

What are the signs and symptoms of hyperkalaemia?

Answer 2

tingling, weakness, flaccid paralysis, chest pain, palpitatons, light-headedness characteristic ECG changes, cardiac dysrhythmias, hypotension

Question 3

What are the signs and symptoms of hyponatraemia?

Answer 3

anorexia, nausea, malaise initially followed by headache, irritability, confusion, weakness, decreased GCS and seizures

Question 4

What are the signs and symptoms of hypernatraemia?

Answer 4

lethargy, thirst, weakness, irritability, confusion, coma and fits along with signs of dehydration

Question 5

What are the signs and symptoms of hypocalcaemia?

Answer 5

SPASMODIC Spasms - carpopedal spasms = Trousseau’s sign (on inflating cuff, wrist and fingers flex/draw together Perioral paraesthesiae Anxious, irritable, irrational Seizures Muscle tone increased in smooth muscle - colic, wheeze and dysphagia Orientation impaired and confusion Dermatitis - atopic/exfoliative Impetigo herpetiformis Chvostek’s sign (corner of mouth twitches when facial nerve tapped over parotid), Choreoathetosis, Cataract, Cardiomyopathy (long QT on ECG

Question 6

What are the signs and symptoms of hypercalcaemia?

Answer 6

bones, stones, groans and psychic moans: abdominal pain, vomiting, constipation, polyuria, polydipsia, depression, anorexia, weight loss, tiredness, weakness, hypertension, confusion, pyrexia, renal stones, renal failure, ectopic calcification, cardiac arrest, ECG showing shortened QT interval

Question 7

What are the signs and symptoms of hypermagnesium?

Answer 7

if severe: neuromuscular depression, hypotension, bradycardia, hyporeflexia, CNS and respiratory depression, coma

Question 8

What are the signs and symptoms of hypomagnesium?

Answer 8

paraesthesiae, ataxia, seizures, tetany, arrhythmias

Question 9

What are the typical ECG changes seen in hyperkalaemia?

Answer 9

flattening P wave, tall tented T waves, widening QRS complex and PR interval, development of deep S waves, sinus arrest with nodal rhythm, sine wave ECG pattern and asystole cardiac dysarrhythmias - ventricular ectopic beats, atrial arrest, atrio-ventricular block, ventricular tachycardia and ventricular fibrillation

Question 10

What are the possible causes for hypernatraemia?

Answer 10

usually due to water loss in excess of sodium ions fluid loss without water replacement - diarrhoea, vomit, burns Diabetes insipidus - suspect if large urine volume, may follow head injury or CNS surgery especially pituitary osmotic diuresis primary aldosteronism - suspect if raised BP, low K and alkalosis (raised HCO3) Iatrogenic - incorrect fluid replacement

Question 11

What are the possible causes for hyponatraemia?

Answer 11

If dehydrated with urinary Na >20 mmol/L = water+Na lost via kidneys

• Addison’s disease
• Renal failure - diuretic phase of renal failure, nephrocalcinosis or medullary-cystic disease
• Diuretic excess
• Osmolar diuresis - incr glucose, incr urea

If dehydrated but urinary Na < 20 mmol/L = water+Na lost other than via kidneys

• diarrhoea
• vomiting
• fistulae
• burns
• rectal villous adenoma
• small bowel obstruction
• trauma
• cystic fibrosis
• heat exposure

Not dehydrated with oedema

• nephrotic syndrome
• cardiac failure
• liver cirrhosis (hyponatraemia may preced oedema)
• renal failure

not dehydrated, no oedema with urine osmolality >100mmol/kg

• SIADH

Not dehydrated, no oedema and urine osmolality <100 mmol/kg

• water overload
• severe hypothyroidism
• gluco-corticoid insufficiency

Question 12

What are the possible causes for hyperkalaemia?

Answer 12

oliguric renal failure

K sparing diuretics

rhabdomyolysis

metabolic acidosis - DM

excess K therapy

Addison’s disease

Massive blood transfusion

burns

Drugs - ACE-I, suxamethonium

Artefactual result

Question 13

What are the possible causes for hypokalaemia?

Answer 13

With alkalosis

• thiazide and loop diuretics
• vomiting
• pyloric stenosis
• cushing’s syndrome/steroids/ACTH
• Conn’s syndrome

With acidosis

• diarrhoea
• renal tubular acidosis/failure
• acetazolamide
• partially treated diabetic ketoacidosis
• rectal villous adenoma
• intestinal fistula

Alkalosis

Purgative and liqourice abuse

Magnesium deficiency

Question 14

What are the possible causes for hypercalcaemia?

Answer 14

Albumin raised:

• dehydration
• cuffed specimen

Albumin normal or low with decreased phosphate:

• primary or tertiary hyperparathyroidism

albumin normal/low, phosphate high/normal and alk phos high:

• bone mets
• sarcoidosis
• thyrotoxicosis
• lithium

albumin normal/low, phosphate high/normal and alk phos normal

• myeloma (incr plasma protein)
• vitamin D excess
• sarcoidosis
• milk-alkali syndrome (raised HCO3)

Question 15

What are the causes of metastatic calcification (cause of hypercalcaemia)?

Answer 15

PARATTHORMONE

Parathyroid hormone levels incr and other causes of hypercalcaemia - sarcoidosis etc

Amyloidosis

Renal failure - relates to PO4

Addison’s disease - adrenal calc

TB nodes

Toxoplasmosis (CNS)

Histoplasmosis

Overdose of vitamin D

Raynaud’s associated diseases - SLE, CREST, dermatomyositis

Muscle primaries/leiomyosarcomas

Ossifying metastases (Osteosarcoma or ovarian mets)

Nephrocalcinosis

Endrocrine tumours - gastrinoma etc

Question 16

What are the causes of hypocalcaemia?

Answer 16

with increased PO₄^3-

• chronic kidney disease
• hypoparathyroidism
• pseudohypoparathyroidism
• acute rhabdomyolysis
• vitamin D deficiency
• hypomagnesaemia

With normal/low PO₄^3-

• osteomalacia
• acute pancreatitis
• over-hydration
• respiratory alkalosis - total Ca normal but decreased ionised Ca due to increased pH -> symptomatic